1 //===- Target.h -------------------------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLD_MACHO_TARGET_H 10 #define LLD_MACHO_TARGET_H 11 12 #include "MachOStructs.h" 13 #include "Relocations.h" 14 15 #include "llvm/ADT/BitmaskEnum.h" 16 #include "llvm/BinaryFormat/MachO.h" 17 #include "llvm/Support/MathExtras.h" 18 #include "llvm/Support/MemoryBuffer.h" 19 20 #include <cstddef> 21 #include <cstdint> 22 23 namespace lld { 24 namespace macho { 25 LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE(); 26 27 class Symbol; 28 class Defined; 29 class DylibSymbol; 30 class InputSection; 31 class ConcatInputSection; 32 33 class TargetInfo { 34 public: 35 template <class LP> TargetInfo(LP) { 36 // Having these values available in TargetInfo allows us to access them 37 // without having to resort to templates. 38 magic = LP::magic; 39 pageZeroSize = LP::pageZeroSize; 40 headerSize = sizeof(typename LP::mach_header); 41 wordSize = LP::wordSize; 42 p2WordSize = llvm::CTLog2<LP::wordSize>(); 43 } 44 45 virtual ~TargetInfo() = default; 46 47 // Validate the relocation structure and get its addend. 48 virtual int64_t 49 getEmbeddedAddend(llvm::MemoryBufferRef, uint64_t offset, 50 const llvm::MachO::relocation_info) const = 0; 51 virtual void relocateOne(uint8_t *loc, const Reloc &, uint64_t va, 52 uint64_t relocVA) const = 0; 53 54 // Write code for lazy binding. See the comments on StubsSection for more 55 // details. 56 virtual void writeStub(uint8_t *buf, const Symbol &) const = 0; 57 virtual void writeStubHelperHeader(uint8_t *buf) const = 0; 58 virtual void writeStubHelperEntry(uint8_t *buf, const Symbol &, 59 uint64_t entryAddr) const = 0; 60 61 // Symbols may be referenced via either the GOT or the stubs section, 62 // depending on the relocation type. prepareSymbolRelocation() will set up the 63 // GOT/stubs entries, and resolveSymbolVA() will return the addresses of those 64 // entries. resolveSymbolVA() may also relax the target instructions to save 65 // on a level of address indirection. 66 virtual void relaxGotLoad(uint8_t *loc, uint8_t type) const = 0; 67 68 virtual const RelocAttrs &getRelocAttrs(uint8_t type) const = 0; 69 70 virtual uint64_t getPageSize() const = 0; 71 72 virtual void populateThunk(InputSection *thunk, Symbol *funcSym) { 73 llvm_unreachable("target does not use thunks"); 74 } 75 76 bool hasAttr(uint8_t type, RelocAttrBits bit) const { 77 return getRelocAttrs(type).hasAttr(bit); 78 } 79 80 bool usesThunks() const { return thunkSize > 0; } 81 82 // For now, handleDtraceReloc only implements -no_dtrace_dof, and ensures 83 // that the linking would not fail even when there are user-provided dtrace 84 // symbols. However, unlike ld64, lld currently does not emit __dof sections. 85 virtual void handleDtraceReloc(const Symbol *sym, const Reloc &r, 86 uint8_t *loc) const { 87 llvm_unreachable("Unsupported architecture for dtrace symbols"); 88 } 89 90 91 virtual void applyOptimizationHints(uint8_t *buf, const ConcatInputSection *, 92 llvm::ArrayRef<uint64_t>) const {}; 93 94 uint32_t magic; 95 llvm::MachO::CPUType cpuType; 96 uint32_t cpuSubtype; 97 98 uint64_t pageZeroSize; 99 size_t headerSize; 100 size_t stubSize; 101 size_t stubHelperHeaderSize; 102 size_t stubHelperEntrySize; 103 uint8_t p2WordSize; 104 size_t wordSize; 105 106 size_t thunkSize = 0; 107 uint64_t forwardBranchRange = 0; 108 uint64_t backwardBranchRange = 0; 109 110 uint32_t modeDwarfEncoding; 111 uint8_t subtractorRelocType; 112 uint8_t unsignedRelocType; 113 114 // We contrive this value as sufficiently far from any valid address that it 115 // will always be out-of-range for any architecture. UINT64_MAX is not a 116 // good choice because it is (a) only 1 away from wrapping to 0, and (b) the 117 // tombstone value for DenseMap<> and caused weird assertions for me. 118 static constexpr uint64_t outOfRangeVA = 0xfull << 60; 119 }; 120 121 TargetInfo *createX86_64TargetInfo(); 122 TargetInfo *createARM64TargetInfo(); 123 TargetInfo *createARM64_32TargetInfo(); 124 TargetInfo *createARMTargetInfo(uint32_t cpuSubtype); 125 126 struct LP64 { 127 using mach_header = llvm::MachO::mach_header_64; 128 using nlist = structs::nlist_64; 129 using segment_command = llvm::MachO::segment_command_64; 130 using section = llvm::MachO::section_64; 131 using encryption_info_command = llvm::MachO::encryption_info_command_64; 132 133 static constexpr uint32_t magic = llvm::MachO::MH_MAGIC_64; 134 static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT_64; 135 static constexpr uint32_t encryptionInfoLCType = 136 llvm::MachO::LC_ENCRYPTION_INFO_64; 137 138 static constexpr uint64_t pageZeroSize = 1ull << 32; 139 static constexpr size_t wordSize = 8; 140 }; 141 142 struct ILP32 { 143 using mach_header = llvm::MachO::mach_header; 144 using nlist = structs::nlist; 145 using segment_command = llvm::MachO::segment_command; 146 using section = llvm::MachO::section; 147 using encryption_info_command = llvm::MachO::encryption_info_command; 148 149 static constexpr uint32_t magic = llvm::MachO::MH_MAGIC; 150 static constexpr uint32_t segmentLCType = llvm::MachO::LC_SEGMENT; 151 static constexpr uint32_t encryptionInfoLCType = 152 llvm::MachO::LC_ENCRYPTION_INFO; 153 154 static constexpr uint64_t pageZeroSize = 1ull << 12; 155 static constexpr size_t wordSize = 4; 156 }; 157 158 extern TargetInfo *target; 159 160 } // namespace macho 161 } // namespace lld 162 163 #endif 164